For embedded pole parts, it is important to strengthen the pole part mechanically in such a way that it is strong enough to withstand a short circuit current. Furthermore, it should be able to withstand mechanical stress when fixing the vacuum interrupter in the braker arrangement if it is operated and then switched. Under these conditions, it is also important to care for dielectric stability.
It is known that the design of an embedded pole part has a cylinder shape form in order to fix the circuit breaker base. There is, however, no transition area, normally from a cylindric form directly to a square form at the bottom.